1. Field of the Invention
The present invention relates to fatty polypropoxylate esters of aliphatic and aromatic monocarboxylic fatty acids. These compounds have unique pigment dispersion and emolliency properties. The fatty polypropoxylate esters of the present invention are particularly useful in the formulation of sunscreen lotions, sunscreen sprays, self-tanning compositions, make-ups and other pigmented products, cold creams, lotions, skin moisturizers, antiperspirants, after shaves, pre-electric shaves, topical pharmaceutical products, lipsticks and cleansing creams. The present invention further relates to topical preparations incorporating the fatty polypropoxylate esters of the present invention.
2. Prior Art
There has been an increased awareness among the public of the potential for skin damage from ultraviolet radiation, with frequent news reports of greater risk from sun-induced photo aging, melanoma, and other skin disorders. The contribution of UVA radiation as well as the widely recognized contribution of UVB radiation to skin damage has engendered the development of a broad range of sunscreen products from the cosmetic industry. Sophisticated sunscreen formulations have been developed which incorporate combinations of UVA and UVB absorbers in vehicles which provide wash-off resistance and enhanced esthetics. Because of the regulatory limitations on the levels at which organic sunscreens may be used in formulations and the desirability for high absorbency formulations (high SPF) with broad spectrum protection, the use of physical sunscreens in conjunction with organic sunscreens in formulations has increased greatly.
Physical sunscreens consist of very finely divided (micronized) inorganic metallic oxides, typically Titanium Dioxide or Zinc Oxide. These micronized physical sunscreens appear transparent on the skin by virtue of their small particle size. Similar to other finely divided particulate products used in cosmetic formulations such as pigments for foundations and makeups, micronized Zinc Oxide and micronized Titanium Dioxide are dispersed within the formulation by mixing, using either low-shear or high-shear methods. In order to make stable, cosmetically acceptable products, uniform dispersions must be produced, with all particles wetted out and which remain in suspension over a period of time without settling, gelling or agglomerating. Producing such stable suspensions has proved to be a challenge, although some successes have been achieved.
For example, U.S. Pat. No. 5,116,604 to Fogel describes the use of neopentanoate esters, in particular isoarachidyl neopentanoate, as cosmetic emollients for sunscreen products. U.S. Pat. No. 5,716,602 to Uick describes sunscreens formulated to include a water resistance agent and an insect repellent. One form has in an aqueous emulsion DEET, a sunscreen agent, an anionic surfactant, an alkylated PVP, and octyldodecyl neopentanoate. Both of these inventions use of Elefac I-205, i.e., Octyldodecyl Neopentanoate.
U.S. Pat. No. 5,476,643 to Fogel describes the use of two specific neopentyl glycol diesters, as wetting, dispersing, spreading and deterging agents for micronized TiO2, ZnO and other pigments. These esters, neopentyl glycol di-2-ethyl hexanoate and neopentyl glycol di-isostearate, are used in varying combinations and may also be used with an emulsifying agent for a water dispersible pigmented make-up cleaner composition.
Emollients such as Finsolv TN (C12–C15 Alkyl Benzoate) and TRIVENT NP-13 (Tridecyl Neopentanoate) have also been employed with some success as dispersants for physical sunscreens, as have various glycols and propoxylates, such as PPG-3 Myristyl Ether. See for example, U.S. Pat. No. 5,928,631 to Lucas which describes a skin composition for controlling environmental malodors on the body. The composition comprises from about 0.1% to about 5%, by weight of a solubilized, water-soluble, uncomplexed cyclodextrin; from about 0.1% to about 36%, by weight of an oil phase selected from the group consisting of emollients, moisturizers, and skin protectants; one or more surfactants, and an aqueous carrier.
U.S. Pat. No. 4,559,226 to Fogel describes self-emulsifying alkoxylate esters useful in cosmetic compositions having a structural formula:

Wherein R1 contains from 2 to 20 carbon atoms and is selected from the group consisting of aliphatic and aromatic substituents and R3 is an alkyl or aryl substituent from 1 to 21 carbon atoms. One of R1 and R3 must contain greater than 8 carbon atoms.                R2 is:        

Wherein x is from 1 to 10 and y is from 1 to 20 and the ratio of y to x is from 2:1 to 10:1. Such esters are both ethoxylated and propoxylated.
Thus there remains a need for superior dispersants with desirable esthetic properties for use in pigmented cosmetic compositions, particularly sunscreen formulations that contain physical sunscreens.
Additionally, since formulators often find it useful to fully disperse pigments, e.g., micronized metallic oxides, in a portion of the oil phase by high shear techniques such as milling, there is a need for forming oil phase dispersions which have a high solids content of pigments, particularly micronized metallic oxides, that are fluid